H22, or a Kseries. Right now everyone is all about the K24(TSX engine) with they head off of the K20(RSX type-s engine), doing the hondata ecu reflash, and some other bolt ons. that combo will produce very respectable power. both are well supported in the aftermarket, both put out decent power, both are DOHC engines. Those are the main reasons. one good thing about the F23 is that the block is very strong and is a good choice for boosting applications, but the internals cannot take high boost. you'll have to upgrade your internals if you plan on running more than 9lbs of boost. If your going the NA route K series or H series is the way to go, if you boost then the F23.